Fire behavior for Firefighter I, ignition to flashover

Heat breaks solid fuels such as wood and plastics down chemically into combustible vapors; that breakdown is pyrolysis.

Oxidation is the reaction with oxygen once the vapors burn, not the process that produces them.

Sublimation is a solid turning straight into gas by a physical change, not decomposition by heat.

Vaporization is a liquid turning into vapor, with no chemical breakdown of a solid.

Smoke explosions usually happen in spaces away from the fire room, such as concealed voids.

In a smoke explosion, smoke that drifted into a void has already mixed with air into its flammable range, so only an ignition source is needed.

The smoke in a smoke explosion is often cooler than backdraft gases, having traveled away from the fire.

Needing air introduced is the mark of a backdraft, the event the question contrasts.

A static spark is an outside ignition source, not heat produced by the fuel itself.

Friction needs surfaces rubbing together, and nothing in a still pile of rags provides it.

Drying oils such as linseed oil oxidize and give off heat; in a pile that heat builds until the rags ignite with no outside source.

Piloted ignition needs an outside flame or spark, which the scenario rules out.

Twenty minutes is closer to legacy-era expectations than to the modern room's result.

About 10 minutes fits neither room; the synthetic furnishings flashed over much sooner.

Close to 30 minutes was the legacy room's time; the trap is mixing up the two results.

In UL's side-by-side tests the modern room flashed over in under 4 minutes, while the legacy room took close to half an hour.

A ventilation-limited fire is waiting for oxygen; opening the door feeds it, and heat release climbs fast unless water reaches the fire.

Incoming air feeds combustion; it does not cool the room enough to hold off flashover.

Letting smoke out does not cool the fire faster than the new air feeds it.

Any opening, including the entry door, changes the flow path and lets air in.

Carbon dioxide is a product of complete burning and will not ignite.

Smoke supplies fuel, not oxygen; air arrives through intake openings.

Smoke carries carbon monoxide, unburned decomposition products and particles that can still burn, which is why a smoke-filled space can ignite.

Water vapor does not burn; treating smoke as steam underestimates its danger.

Rollover warns of flashover in a fire that still has air, not of backdraft.

Light, lazy smoke points to a smaller or early fire rather than a starved, pressurized one.

Smoke drawn in and pushed out of gaps signals a hot, oxygen-starved space that may ignite violently when air enters.

A fire already venting has its own air supply, which makes backdraft less likely.

Volume, velocity, density and color are the four attributes used to read smoke.

Odor is not a reading attribute and says little about the fire's location or stage.

Smoke temperature cannot be judged by eye; heat is inferred from velocity and color.

Smoke height is not part of the model; velocity and volume carry that information.

This is ten times too small and makes steam production look harmless.

Water expands about 1,700 times when it turns to steam at its boiling point.

About 270 is the liquid-to-vapor ratio of propane, a different figure firefighters learn.

17,000 times overstates steam expansion by a factor of ten.

A decaying fire gives off lazier, lighter smoke as its fuel runs out.

An incipient fire makes a little light smoke, not a dense turbulent push.

Steam is white and clears quickly as it cools; it is not black.

Thick, dark, fast and turbulent smoke shows a hot, fuel-rich fire under pressure, a classic flashover warning.

Oxygen-enriched means air with more oxygen than normal, as near a leaking oxygen cylinder, not simply a fire with enough air.

When air is plentiful, growth depends on the burning material and its arrangement, the definition of a fuel-controlled fire.

Fully developed is a stage of fire growth, not a description of what limits it.

A ventilation-limited fire has more fuel than its air supply can burn, the opposite case.

Ceiling height changes how heat collects, not the fuel present.

Fire load is the potential heat in a space, so it depends on how much fuel is present and how much heat that fuel can release.

Wall ratings describe containment, not the fuel inside the room.

Openings affect how fast fuel burns, not how much fuel is there.

Whether a vapor is heavier than air depends on its molecular weight, not on the day's temperature.

Less vapor on a hot day reverses the effect of temperature on evaporation.

Warmth raises a liquid's vapor pressure, so more vapor forms and the flammable zone around the spill grows.

Flash point is a fixed property of the liquid; the weather does not change it.

Gases cannot move against a pressure difference; this reverses the direction.

Gases flow from the high-pressure fire area toward lower-pressure openings, carrying heat toward the exhaust.

Air enters at the intake and heat leaves at the exhaust; this reverses the path.

Hot gases move away from the fire toward cooler, lower-pressure areas, not the reverse.

Above the upper limit there is too much fuel and too little air for the mixture to burn, though ventilation can bring it back into range.

Too lean describes a mixture below the lower limit, the other end of the range.

The flammable range ends at the upper limit, so a mixture above it is outside the range.

The most easily ignited mixtures lie inside the range, not above it.

The joule is the SI unit of energy and is not defined by heating a pound of water.

A kilowatt is a rate of energy use, power, not an amount of heat.

A calorie is the metric counterpart, based on one gram of water and 1°C.

A British thermal unit is the heat needed to raise one pound of water by 1°F, the customary US unit of heat.

Conduction moves heat slowly through solids and cannot bring a whole room to ignition at once.

Flame contact ignites items one at a time; flashover is near-simultaneous ignition driven from above.

The hot ceiling layer radiates heat down onto every exposed surface until the contents reach ignition temperature almost at once.

Convection carries hot gases up to build the ceiling layer; near the floor it brings in cooler air, not ignition heat.

Steam and churned smoke usually make visibility worse, not better.

A wide fog in hot gases makes a large amount of steam, not less.

Mixing the hot gases downward raises heat near the floor, where crews and victims are, instead of lowering it.

Fog turns to steam and stirs the hot gases at the ceiling down toward the floor, so the layered heat that kept the lower air survivable is lost.